Conventionally, as a large volume data recording medium, a read only medium which is called a CD-ROM (Compact Disc-Read Only Memory) is available. There is available a write-once type disc-like recording medium called Compact Disc-Recordable (CD-R) in which data can be recorded only once by forming a recording layer on the CD-ROM.
This CD-R can be played back by using a conventional CD-ROM drive so that all the data is recorded and prepared, for example, on a hard disc with the result that the CD-R in which writing is completed can be used as a CD (Compact Disc) by writing all the data in the CD-R.
By the way, since the CD-R having such a constitution can be written only once, it is difficult to rewrite the data in an area where data is written once in the same area so that it is difficult to use the CD-R as a rewritable recording medium like a so-called floppy disc.
In the case where recorded data is renewed with a write once disc type CD-R disc, it is difficult to rewrite an area which has been once written. Consequently, work is required to rewrite the renewed data on a new area in this case. Due to such characteristics of the write once type recording medium, in the case where an attempt is made to rewrite data by using the write once type CD-R disc, the usable residual capacity of the CD-R disc will be decreased with the result that there arises a problem in that it becomes difficult to write the data which is about to be renewed on the memory once there is no room for the usable capacity.
The present invention has been made in view of the aforementioned problem, and the invention provides an information processor and a method of information processing wherein the write once type recording medium can be used as if the recording medium was a rewritable type recording medium and the usable residual capacity can be monitored.